Production of high purity salt from high sulfate salt deposits
OwnerJerome A. Lukesinventor
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Abstract
A subterranean salt deposit is solution mined, and the resulting calcium- and sulfate-contaminated brine is treated, e.g., by soda ash, to precipitate insoluble calcium compounds. The resulting slurry is settled, and the effluent clear brine is evaporated in a series of solar ponds to produce high-grade sodium chloride. The brine becomes progressively more concentrated with respect to sodium sulfate as it moves through the solar ponds. The sulfate-enriched brine may be recycled to the solution mine, evaporated to form a sulfate-contaminated sodium chloride crystal crop, or it may be subjected to winter cooling to remove sulfate values as Glauber's salt, the residual brine being recycled to the solar ponds or the solution mine.
Claims7
A process comprising:
- contacting a subterranean deposit containing NaCl contaminated with calcium and sulfate with an aqueous solvent to produce an aqueous brine containing dissolved calcium and sulfate values;
- transferring said contaminated brine to a calcium treatment zone and contacting said brine with a reagent to insolublize said calcium values, thereby producing a slurry with an aqueous phase substantially free from dissolved calcium values;
- transferring said aqueous phase to the first of a plurality of solar evaporation ponds arranged in a production zone for series flow such that the brine is maintained at its saturated concentration with respect to NaCl throughout the zone and becomes progressively more concentrated with respect to sulfate in successive ponds, thereby producing an NaCl crystal crop in each of said ponds;
- adjusting the flow rate of brine through said production zone to maintain the concentration of sulfate in the last of said ponds below its saturated concentration, thereby producing a sulfate-enriched effluent brine from said production zone;
- removing said sulfate-enriched effluent brine from said production zone;
- and harvesting the NaCl crystal crop from individual solar evaporation ponds of said production zone.
Dependencies are inferred from the claim text.